I have question - I noticed that the right side of my Tamiya Abrams is about 4-5mm lower than the left side - is it normal or any mistake?

It’s probably normal - tank turrets are often not geometrically symmetrical aside from the obvious difference in cupolas, optics, etc. because the interior is not symmetrically laid out either.

On torsion bar larger RC tanks like the Abrams it is not uncommon to have one side sit slightly lower than the other. 4-5mm is a lot of difference especially for a Tamiya Abrams. Both of mine sit pretty much level.

Thank You guys for reply and help. Now Im wondering if I made any mistake in tank assembly - is it possible?

Yes. It's possible the springs are installed incorrectly.

I must correct myself as I misunderstood your question completely.

If the chassis is not sitting level then there is likely a mistake in assembling the torsion bars and suspension arms. However, all the torsion bars are the same part number so you may wish to check if parts are correctly fitted.

Thank You very much for explanations